1556. Thousand Separator-千位分隔数

Given an integer n, add a dot (".") as the thousands separator and return it in string format.

Example 1:
Input: n = 987
Output: "987"

Example 2:
Input: n = 1234
Output: "1.234"

Example 3:
Input: n = 123456789
Output: "123.456.789"

Example 4:
Input: n = 0
Output: "0"

Constraints:

• 0 <= n < 2^31

Solution in python:

class Solution:
    def thousandSeparator(self, n: int) -> str:
        if n == 0:
            return "0"
        c = 0
        result = ""
        while n > 0:
            n, r = divmod(n, 10)
            result = str(r) + result
            c += 1
            if c % 3 == 0 and n > 0:
                result = '.' + result
        return result